Thus in many parts of the world the navel-string, or more commonly the afterbirth, is regarded as a living being, the brother or sister of the infant, or as the material object in which the guardian spirit of the child or part of its soul resides. Further, the sympathetic connexion supposed to exist between a person and his afterbirth or navel-string comes out very clearly in the widespread custom of treating the afterbirth or navel-string in ways which are supposed to influence for life the character and career of the person, making him, if it is a man, a nimble climber, a strong swimmer, a skilful hunter, or a brave soldier, and making her, if it is a woman, a cunning sempstress, a good baker, and so forth. Thus the beliefs and usages concerned with the afterbirth or placenta, and to a less extent with the navel-string, present a remarkable parallel to the widespread doctrine of the transferable or external soul and the customs founded on it. Hence it is hardly rash to conjecture that the resemblance is no mere chance coincidence, but that in the afterbirth or placenta we have a physical basis (not necessarily the only one) for the theory and practice of the external soul. The consideration of that subject is reserved for a later part of this work. A curious application of the doctrine of contagious magic is the relation commonly believed to exist between a wounded man and the agent of the wound, so that whatever is subsequently done by or to the agent must correspondingly affect the patient either for good or evil. Thus Pliny tells us that if you have wounded a man and are sorry for it, you have only to spit on the hand that gave the wound, and the pain of the sufferer will be instantly alleviated. In Melanesia, if a man's friends get possession of the arrow which wounded him, they keep it in a damp place or in cool leaves, for then the inflammation will be trifling and will soon subside. Meantime the enemy who shot the arrow is hard at work to aggravate the wound by all the means in his power. For this purpose he and his friends drink hot and burning juices and chew irritating leaves, for this will clearly inflame and irritate the wound. Further, they keep the bow near the fire to make the wound which it has inflicted hot; and for the same reason they put the arrow-head, if it has been recovered, into the fire. Moreover, they are careful to keep the bow-string taut and to twang it occasionally, for this will cause the wounded man to suffer from tension of the nerves and spasms of tetanus. "It is constantly received and avouched," says Bacon, "that the anointing of the weapon that maketh the wound will heal the wound itself. In this experiment, upon the relation of men of credit (though myself, as yet, am not fully inclined to believe it), you shall note the points following: first, the ointment wherewith this is done is made of divers ingredients, whereof the strangest and hardest to come by are the moss upon the skull of a dead man